Telwin MIG-MAG Manual De Instrucciones página 25

5.7 REPLACING THE LINER IN THE TORCH (FIG. H)
Before proceeding to replace the hose, lay out the torch cable straight without any
bends.
5.7.1 Coiled hose for steel wires
1- Unscrew the nozzle and contact tip on the torch head.
2- Unscrew the hose locking nut on the central connector and remove the old hose.
3- Insert the new hose into the cable-torch duct and push it gently until it comes out of
the torch head.
4- Tighten up the hose locking nut by hand.
5- Trim off all the excess protruding hose pressing it slightly; remove it from the torch
cable again.
6- Smooth the part where the hose was cut and reinsert it into the cable-torch duct.
7- Tighten up the nut again using a spanner.
8- Reassemble the contact tip and nozzle.
5.7.2 Synthetic hose for aluminium wires
Carry out operations 1, 2, 3 as given for the steel hose (ignore operations 4, 5, 6, 7, 8).
9- Re-tighten the contact tip for aluminium, making sure it comes into contact with the
hose.
10-At the other end of the hose (torch connector end) insert the brass nipple and the
OR ring and, keeping slight pressure on the hose, tighten the hose locking nut.
Extract the capillary pipe for steel hoses from the wire feeder torch connector.
11-THE CAPILLARY PIPE IS NOT REQUIRED for aluminium hoses of diameter 1.6-
2.4mm (coloured yellow); the hose is therefore inserted into the torch connector
without it.
Cut the capillary pipe for aluminium hoses of diameter 1.2-1.6mm (coloured red) to
approx. 2mm shorter than the steel pipe, and insert it into the free end of the hose.
12-Insert and lock the torch into the wire feeder connector, mark the hose at 1-2mm
from the rollers, take the torch out again.
13-Cut the hose to the required size, without distorting the inlet hole.
Reassemble the torch in the wire feeder connector and assemble the gas nozzle.
6. WELDING: DESCRIPTION OF THE PROCEDURE
6.1 METHODS OF METAL TRANSFER
6.1.1 Short arc
The melting of the electrode wire and the detachment of the drop is produced by
repeated short circuits (up to 200 times per second) from the tip of the wire to the
molten pool.
Carbon and mild steels
- Suitable wire diameter:
- Welding current range:
- Arc voltage range:
- Suitable gases:
Stainless steels
- Suitable wire diameter:
- Welding current range:
- Arc voltage range:
- Su itable gases:
Aluminium and alloys
- Suitable wire diameter:
FIG. H
5 6
8 9
0.6-1.2mm
40-210A
13-23V
CO , mix Ar/CO , Ar/CO /O
2 2 2 2
0.8-1mm
40-160A
14-20V
mix Ar/O , Ar/CO (1-2%)
2 2
0.8-1.6mm
1
10
- 25 -
- Welding current range:
- Arc voltage range:
- Suitable gases:
- Wire stick out:
Generally, the contact tip should be flush with the nozzle or protrude slightly when
using the thinnest wires and lowest arc voltages; the length of free wire (stick-out) will
normally be between 5 and 12mm. Select the minimum reactance outlet for carbon or
mild steels with C0 gas (wire diameters 0.8-1.2mm) and average for the same material
2
with Ar/CO gas, high for stainless steel and aluminium.
2
Application: Welding in all positions, on thin material or for the first passage in bevelled
edges, with the advantage of limited heat transfer and highly controllable pool.
Note: SHORT ARC transfer for welding aluminium and alloys should be used with great
care (especially with wires of diameter >1mm) because the risk of melting defects may
arise.
6.1.2 Spray arc
Higher voltages and currents than for "short arc" are used here to achieve the melting of
the wire. The wire tip does not come into contact with the molten pool; an arc forms from
the tip and through it flows a stream of metallic droplets. These are produeced by the
continuous melting of the electrode wire without short-circuits involved.
Carbon and mild steels
- Suitable wire diameter:
- Welding current range:
- Arc voltage range :
- Suitable gases :
Stainless steels
- Suitable wire diameter:
- Welding current range:
- Welding voltage range :
- Suitable gases :
Aluminium and alloys
- Suitable wire diameter:
- Welding current range:
- weld ing voltage range :
- suitable gases :
The contact tip should generally be 5-10mm inside the nozzle, the higher the arc
voltage the further inside; the length of free wire (stick-out) should normally be between
10 and 12mm. Use the minimum reactance outlet.
Application: Horizontal welding with thicknesses of at least 3-4mm (very fluid pool);
execution rate and deposit rate are very high (high heat transfer).
6.2 ADJUSTING THE WELDING PARAMETERS
6.2.1 Shielding gas
shielding gas flow rate should be:
short arc: 8-14 l/min
spray arc: 12-20 l/min
depending on welding current intensity and nozzle diameter.
11
12 13
75-160A
16-22V
Ar 99.9%
5-12mm
0.8-1.6mm
180-450A
24-40V
mix Ar/CO , Ar/CO /O
2 2
1-1.6mm
140-390A
22-32V
mix Ar/O , Ar/CO (1-2%)
2 2
0.8-1.6mm
120-360A
24-30V
Ar 99.9%
2
3 4 7
2